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Can’t quite seem to figure out how to finish this roughed in basement. The entire waste system under the concrete is 4″ PVC. What is the best method to install a shower pan to this pipe? Is there an adaptor that needs to be glued floor level to accept the drain tail? Thanks for any input, and thanks Fine Homebuilding for this form and a fine magazine.
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Replies
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Mike,
When you say "roughed in basement" do you mean a bathroom has been laid out with 4" stub ups for all the fixtures or do you simply have a 4" drain under the slab?
Steve
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Steve:
Thanks for responding. The plumbing in the basement is laid out for a full bathroom, with 4" stub ups for shower and toilet, and 2" vents. The problem is that the hole in the shower pan is about 2" in diameter, and the stub up is 4" PVC. How do I connect up the drain hardware for the shower to that 4" pipe? there must be some sort of reducer ,I guess, but what it looks like and where I can get one is beyond me.. Thanks again, Steve.
Duffey
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Mike,
There are two types of shower pans and each has it's own fittings. The first is a traditional mud and liner pan that is built on site. The second is a premade pan (to include fiberglass shower stalls and variants). For residential showers a 2" drain is standard. However, there are two drain fittings, one for the traditional pan and one for the moulded unit. The mud pan fitting is glued to the stub. To provide necessary recess in the slab, the plumber will typically use a length of 4" PVC around the stub (as a form or dam) and fill the void with sand. After the concrete is plced and cured the sand is removed, the stub and form are trimed to length and the fitting is glued on. Is there any chance your 4" shower drain is a form and there is another 2" drain inside? For preformed shower pans the fitting is attached to the pan and slips over the stub. It has a rubber seal. The stub must be precisely placed to ensure that the shower fits the fraiming. When the plumber roughs in the below slab drain for a shower he will install a trap to prevent sewer gas from comming up the shower drain. You need to insure that there is a trap in the shower drain under your floor. If your 4" shower drain does not have a trap it may be a vent stack and not a drain. If all of the stubs ups are open check to see if any of the 2" have traps - it is possible one of them is the shower drain. To check, poor some water down the stub. A trap will hold water. A drain or vent will pass the water on. If none of the drains or vents have traps you are going to have to bust concrete or elevate your shower so you can put a drain and trap under it but above the floor. If the 4" drain has a trap (I will be surprised if it does) then you can adapt down to 2" and stub up. Any thought to how you will drain the vanity? Could the second 2" drain be a drain for the vanity or alternatively, could the vanity be drain into the 4" line if it is really a stack? House I had in St Louis came with an unfinished basement and a stubbed out bathroom. All of the drains were there but when we tried to figure out a way to build a bathroom it just was not possible. If we put everything where it was stubbed out it would have been impossible to get in or out because the HVAC was in the only possible location for a door. We eliminated the shower and put the door in its place. My point - I am not sure these kind of "future use" basement bathrooms are stubbed out to any plan. One possibility is to locate the plumber who did the work and ask for an explanation. Most likely, you will have to do some detective work to sort it all out. If there are any supply lines in place they can help tell the story. Keep us posted. E-mail me if you think I can help.
*Mike, I suggest you consult the plumber who did the original work. A four inch stub for the toilet would be correct but not for a shower. A 2 inch stub is what you would normally see and below that would be a P-trap and then the 2 inch line would continue to an intersection with the main. Your drain assembly is then attached to the stub when you install the pan. There are reducers available but with a 4 inch stub my first impression is that the P-trap is missing and was not noticed or was ignored during the rough inspection. (This was a permitted job, right)? You may be looking at a retro-fit - that means breaking up your floor. Sorry, but at long distance that's how I read it.Comments? Ralph
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Thanks for responding..
The deal was that the original plumber said that since the PVC was to be below concrete, he felt that 4" was the best way to avoid any future problems with blockages.. Once the concrete was poured around the pipes, I realized that there was no way I knew to join a pan to the 4" pipe. Someone told me to cut down and put a 4" to 2" reducer on there, but that means breaking up concrete, maybe hurting the pipe, a huge amount of work. I wondered if there isn't something I could mount to the 4" pipe at floor level that would accept a 2" drain from the shower pan.. Am I putting this clearly? Thanks again.
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Mike, read Steve Hansens reply again, carefully. You MUST have a trap installed under the slab for the shower drain and the norm for this drain is 2 inch pipe. If you are sure this particular 4 inch pipe was intended to be the shower drain and it does not have a trap you will have to resign yourself to the fact that you have some concrete breakup and repair to do. Even though there is an adapter available to reduce 4 inch directly to 2 inch do not circumvent the proper design of your waste system. You do not want vermin or nasty sewer gas coming up in your house. Dig down far enough so you can install a 2 inch stub, a 2 inch trap and then you can use the reducer to connect to the main 4 inch pipe. While you're at it you might also make sure that the whole system is properly vented. Hold your plumber firmly by the neck until you get all the proper answers.
Comments? Ralph
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Ralph: Thanks for responding. I helped to saw the concrete and lay the roughed in PVC. The system is for a full bath, with the fixtures all along one wall. Starting from the far end, it is 4" stub up for shower drain, 2" vent, 4" stub up for toilet, 2" vent, and 2" stub up for sink. In your entry, you mention that there is an adapter for 4" to 2". If I cut the 4" shower drain pipe flush with the floor, can I put the 4" to 2" on the pipe , and install the shower base from there? I know if I had access below the level of the finished concrete I could just cut the 4" a few inches below the floor level, install a 4"to 2" adapter and install the drain, but the concrete has been trowelled very smoothly, (by me) so that it is level around the 4" pipe. I think I should have left some room in the concrete around that pipe. Well, next time..
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Can't quite seem to figure out how to finish this roughed in basement. The entire waste system under the concrete is 4" PVC. What is the best method to install a shower pan to this pipe? Is there an adaptor that needs to be glued floor level to accept the drain tail? Thanks for any input, and thanks Fine Homebuilding for this form and a fine magazine.